As to processes for producing aryl carbonates, there are known, for example, the following processes: a process including a transesterification reaction between a carbonic acid ester and an aromatic hydroxy compound; and a process including disproportionation by a transesterification reaction of alkyl aryl carbonates. These transesterification reactions need catalysts. For the catalysts, there have been proposed various catalysts: for example, Lewis acids or compounds which produce Lewis acids; Ti-based or Al-based compounds; lead compounds; organotin compounds; and so forth.
In addition, as to processes for producing aryl carboxylates, there are known, for example, the following processes: a process including esterification of an aromatic hydroxy compound with an aliphatic carboxylic acid; a process including esterification of phenol with high active reaction materials, such as isopropenyl acetate and diketene; and so forth. However, any process using a solid heterogeneous catalyst is not yet known in industrial production processes including a transesterification reaction of an aliphatic carboxylate with an aromatic hydroxy compound.
All the catalysts used in the above-mentioned processes are homogeneous and react in condition of being dissolved in raw materials and so are difficult to separate after reactions. Therefore, these catalysts have problems in industrial practical use.
In order to solve the problems about separation, Japanese Official Patent Gazette (Kokoku) No. Showa 61-5467 proposed to use a silica-titania composite oxide as a heterogeneous catalyst, and Japanese Official Patent Provisional Publication (Kokai) No. Heisei 4-266856 proposed to use titanium oxide having high surface area as a catalyst. However, the silica-titania composite oxide catalyst has strong character as an acid and easily cause decarboxylation that is a side reaction; and the titanium oxide catalyst has low activity. In addition, although both the catalysts are heterogeneous at the initiation of a reaction, a considerably large proportion of catalyst components dissolve into raw materials as the reaction progresses. So these catalysts substantially do not differ from homogeneous ones at all, and are not sufficient as means of solving the problems.